Interplay of Ferritin Accumulation and Ferroportin Loss in Ageing Brain: Implication for Protein Aggregation in Down Syndrome Dementia,Alzheimer’s,and Parkinson’s Diseases

Iron accumulates in the ageing brain and in brains with neurodegenerative diseases such as Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), and Down syndrome (DS) dementia. However, the mechanisms of iron deposition and regional selectivity in the brain are ill-understood. The identification of several proteins that are involved in iron homeostasis, transport, and regulation suggests avenues to explore their function in neurodegenerative diseases. To uncover the molecular mechanisms underlying this association, we investigated the distribution and expression of these key iron proteins in brain tissues of patients with AD, DS, PD, and compared them with age-matched controls. Ferritin is an iron storage protein that is deposited in senile plaques in the AD and DS brain, as well as in neuromelanin-containing neurons in the Lewy bodies in PD brain. The transporter of ferrous iron, Divalent metal protein 1 (DMT1), was observed solely in the capillary endothelium and in astrocytes close to the ventricles with unchanged expression in PD. The principal iron transporter, ferroportin, is strikingly reduced in the AD brain compared to age-matched controls. Extensive blood vessel damage in the basal ganglia and deposition of punctate ferritin heavy chain (FTH) and hepcidin were found in the caudate and putamen within striosomes/matrix in both PD and DS brains. We suggest that downregulation of ferroportin could be a key reason for iron mismanagement through disruption of cellular entry and exit pathways of the endothelium. Membrane damage and subsequent impairment of ferroportin and hepcidin causes oxidative stress that contributes to neurodegeneration seen in DS, AD, and in PD subjects. We further propose that a lack of ferritin contributes to neurodegeneration as a consequence of failure to export toxic metals from the cortex in AD/DS and from the substantia nigra and caudate/putamen in PD brain.     

Investigations on the Low Temperature Methanation with Pulse Reaction of CO

The low temperature methanation via pulse reaction is investigated and the application of data reduction by moment analysis is shown. Pulse experiments were performed in the temperature range from 200 to 270 °C with CO pulses in a diluted H₂ gas stream. The appearance and shape of the resulting CH₄ signal indicate limiting kinetic processes. The signals are analyzed using a combination of basic methods and moment analysis, which allows condensing data from transient experiments for improved interpretation.     

Explicit construction of families of LDPC codes with no 4-cycles

Low-density parity-check (LDPC) codes are serious contenders to turbo codes in terms of decoding performance. One of the main problems is to give an explicit construction of such codes whose Tanner graphs have known girth. For a prime power q and m/spl ges/2, Lazebnik and Ustimenko construct a q-regular bipartite graph D(m,q) on 2q/sup m/ vertices, which has girth at least 2/spl lceil/m/2/spl rceil/+4. We regard these graphs as Tanner graphs of binary codes LU(m,q). We can determine the dimension and minimum weight of LU(2,q), and show that the weight of its minimum stopping set is at least q+2 for q odd and exactly q+2 for q even. We know that D(2,q) has girth 6 and diameter 4, whereas D(3,q) has girth 8 and diameter 6. We prove that for an odd prime p, LU(3,p) is a [p/sup 3/,k] code with k/spl ges/(p/sup 3/-2p/sup 2/+3p-2)/2. We show that the minimum weight and the weight of the minimum stopping set of LU(3,q) are at least 2q and they are exactly 2q for many LU(3,q) codes. We find some interesting LDPC codes by our partial row construction. We also give simulation results for some of our codes.     

Dependence of damage efficiency of ions in diamond on electronic stopping

Natural diamond single crystals were irradiated at room temperature with 75 keV carbon and 80 keV argon ions at fluences exceeding the graphitization dose. The resulting damage depth profiles before and after rapid annealing at 1500 K were obtained by -particle channeling analysis. Measurements were done both at back- and forward scattering angles using conventional surface barrier detectors and an electrostatic analyzer system, respectively. Boundary positions of the graphitic layers were determined and compared with the corresponding depth-dependent elastic and inelastic energy deposition graphs to extract critical damage energy densities. The obtained values increase strongly with inelastic energy deposition rate, indicating a significant reduction of the ions’ damage efficiency due to irradiation induced annealing by electronic stopping.     

Molecular beam epitaxy of quantum wires and quantum dots on patterned high-index substrates

Using a novel growth mechanism on patterned high-index GaAs (311)A substrates we have developed a new concept to fabricate quantum wires and quantum dots as well as coupled quantum wire-dot arrays by molecular beam epitaxy. The combination of self-organized growth with lithographic patterning and the assistance of atomic hydrogen produces these quasi-planar lateral nanostructure arrays with unprecedented uniformity in size and composition and with controlled positioning on the wafer. The sought for one- and zero-dimensional nature of these quantum wire and quantum dot arrays manifests itself in the superior optical properties. To functionalize our lateral semiconductor quantum wire and quantum dot arrays with the properties of magnetic thin films, epitaxial Fe layers have been grown on GaAs (311)A. Defect free Fe layers are obtained on As-saturated GaAs surfaces. The large electrical conductivity of thin Fe layers indicates reduced Fe-GaAs interface compound formation. An unusual in-plane spontaneous Hall-effect is observed in these epitaxial Fe layers of reduced symmetry.     

A programmable temperature monitoring device for tagging smallfish: a prototype chip development

This paper describes the design of an archival temperature monitoring tag to be used to collect habitat information of Atlantic salmon during the marine phase of the species' natural history. The monolithic circuit should not exceed an average power dissipation of 3.4 μW, so that a small 3V, 30 mAh lithium battery will provide the device with the expected lifetime of 3 years. The thermal sensor is realized by a p-n-junction, The recorded junction voltages are digitized and stored in static RAM cells. The tag is programmed before deployment by an external computer via a serial interface. The device's temperature-monitoring protocol is defined at this stage. Upon retrieval of the tag, the stored temperature values will be transferred to a computer where the geographical location of the fish at the actual sampling time will be deduced through retrospective navigation based on known sea temperature distribution     

Antibiotic-resistant pneumococci in pediatric disease

In 152 patients with an early pregnancy which was subsequently normal, we measured the maternal serum levels of estradiol (E2), progesterone (P4) and prolactin (PRL) as well as the diameter of gestational sac (GS) and the crown-rump length (CRL) of the embryo by transvaginal ultrasonography. The maternal serum level of E2 had the closest statistically significant correlation with both the GS diameter (r = 0.769, P < 0.01) and the CRL (r = 0.736, P < 0.001). P4 and PRL concentrations showed less correlation with embryo development.     

Control system design using radioactive pickoff

An accelerometer can be constructed using a radioactive proof mass, the position of which can be determined on the basis of the difference between the mean number of emitted charged particles detected at opposite walls when the proof mass is not centered. If the emission rate is relatively small, however, the mean counting rate is very noisy; satisfactory operation requires optimum signal processing. The control system, designed by linear stochastic control theory, generates forces that tend to keep the proof mass centered between walls of the instrument and simultaneously produces an estimated acceleration output. The Poisson-type noise of the pickoff is approximated by Gaussian noise; the acceleration input is modeled as a random walk. It is found by simulation that for an instrument with 1.0 inch spacing between the walls, the proof mass excursion can be confined to a peak-to-peak amplitude of 0.36 inch in a severe acceleration environment. The accelerometer output tracks a constant input without error and, when the input acceleration has a random component, the rms error is of the order of ten percent of the random component.     

Theory of a nonwiggler collective free electron laser in uniform magnetic field

A nonwiggler free electron laser, operating in uniform guide magnetic field, is analyzed. The amplifier problem is solved self-consistently on the basis of the kinetic theory. It is shown that the asymmetry in the azimuthal distribution of the electrons' momentum leads to a coupling between the transverse and the space-charge modes. This, in turn, enhances the gain in the amplifier. In the case of a cold beam, with the electrons gyrating coherently, the spatial growth in the collective nonwiggler free electron laser (FEL) is comparable to that found in conventional free electron lasers operating in similar regimes.